The treatment of corroded copper, brass, and bronze ship fastenings often presents conservators with widely different responses from apparently similar or identical materials. This study demonstrates that the electrochemical techniques of measuring the polarization resistance and corrosion potentials of objects are powerful tools in resolving the differences in materials performance. The effects of sea water agitation, pH, and dissolved oxygen on the above corrosion parameters are discussed. In the absence of any discernible differences in chemical composition, widely divergent corrosion rates can be rationalized in terms of the metal microstructure and the stresses induced at manufacture or during the shipwrecking process.